Date: Mon, 02 Jul 2001 08:56:02 +0200

Author: Urs Lauterburg

Subject: Re: water waves perpendicular to the piston


William et al.

A while back I conditioned a little old fashioned traditional loudspeaker
with silikon spray to make it water proof. Putting the loudspeaker on its
back on a table and filling it with some water, then driving it first with
sine waves, then with music, made wonderful standing wave patterns, similar
of course to the famous Chladnei patterns. To make this visible to a large
crowd is a challenge since lighting has to be carefully tuned with large
hazy lights to make a nice video enlargement possible. I had to rely
heavily on my good old knowledge gained when I was a studio photographer
for some time way back in the 80ies.

The demo could really be performed as some kind of analogon for atom
quantum states according to Schrödinger's equation. And yes, i think to
fill a loudspeaker with water is my own idea but then again maybe someone
else has already ventured into this too. I know that in the old days
speakers where filled with mercury, which is behaves better for standing
wave patterns but is not healthy at all.

Regards to the list and see you in Rochester in a few weeks


Urs Lauterburg
Physics Edutainer
University of Bern

>On Wed, 27 Jun 2001, Jerry DiMarco wrote:
>> What you describe does not sound like standing waves to me. I think
>> there might be too many variables in your setup. If this happened in a
>> controlled experiment, then it would be worth looking into. But a "noodle"
>> (as my kids call them) in a swimming pool is a bit too unpredictable for
>Um... Before judging, I suggest attempting the experiment. I find these
>strange waves fascinating, but I can certainly see how a verbal
>description might not stimulate curiousity in the same way that direct
>observation would. If someone listens to my description, they might say
>"ah, it's probably a mistake." But if they manage to produce the waves
>themselves, they might say "WEEEEEIRD!" I did when I saw the
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